The double reed is placed between the lips and blown, which sets the two reeds vibrating against each other. They open and close very quickly, thereby sending little puffs of air into the air column inside the instrument, which is stimulated to move in sympathy.
As on all woodwinds it is primarily the keywork that is used to produce the various pitches. The technique of overblowing - the bassoon overblows to the octave – is largely replaced by the use of speaker keys. Five of the tone holes are closed directly by the fingers, the rest by keys.
The fundamental scale of the bassoon ranges from F2 to F3. This compass is extended downward to Bb1 with the aid of the keys.
By attaching a so-called A bell, which is fixed to the customary Bb bell, A1 is playable too.
The notes from F#3 to D4 are produced by overblowing the fundamental scale (first-degree overblowing), the fingering is the same as that for the lower octave.
For the notes Eb4 to Eb5 (and above) special fingerings or combinations are used.
It is thanks to two factors that bassoon fingering is possible at all bearing in mind the instrument’s size:
1. keys with very long levers;
2. the tube walls of the bassoon are exceptionally thick, which makes it possible to place the fingerholes at an angle to the wood. Bassoonists can therefore reach all five fingerholes with no difficulty. The thickness of the walls is also an important factor in determining the instrument’s timbre.
Due to its U shape, condensation from exhaled air or saliva collects in the instrument. To prevent decay the boot and the tone holes on the wing joint are lined with rubber or a similar material.
To play, the bassoon is held diagonally across the body with the left hand at the top and the right hand at the bottom. The left hand covers the five fingerholes and sixteen or so keys on the wing joint and long joint, the right hand the approximately eleven keys on the boot.
The size and weight of the bassoon means that it must be supported while it is being played. Bassoonists hold the instrument with the aid of a strap which goes round the neck or shoulders and is hooked into a ring on the instrument’s boot. For playing in the sitting position the belt is used as an alternative – the musician sits on a leather strap with a pouch at the end which holds the U-bend.